There are various different types of backpacks with various different shapes and features that are manufactured and sold. Tombstone shaped backpacks are very popular because their main interior storage compartment can be easily accessed via their inverted u-shaped zipper closure that tracks around an inverted u-shaped aperture in an upper periphery of such backpacks. However, tombstone shaped backpacks that include an inverted u-shaped zipper closure are typically not waterproof, unless very heavyweight and expensive waterproof zippers are utilized, such as those sold by TITEX GmbH of Heilsbronn, Germany, under the TRIZIP™ brand. A problem with using such very heavyweight and expensive waterproof zippers on tombstone shaped backpacks is that such zippers are incredibly difficult to open around an inverted u-shaped path. Additionally, such zippers are very expensive, and thus, increase manufacturing costs.
Roll-top backpacks, on the other hand, can typically be made waterproof more easily and less expensively by creating a sealed compartment through a compressed roll of welded waterproof (e.g., plastic coated) fabric. However, a drawback of a typical roll-top backpack is that the main interior storage compartment is difficult to access. More specifically, with a typical roll-top backpack, it is difficult to access deep into the bag because the fabric used for the rolling function at the top makes the backpack very tall when the top is unrolled. Further, there are typically multiple buckles to keep the fabric roll compressed, which can be more user-intensive than a single zipper closure that is used in a typical tombstone shaped backpack.